Color developing solutions containing an aromatic primary amine color developing agent have been employed for the purpose of forming color images and, at present, are basic to image formation in color photography. However, as is well known, the above described color developing solution has the problem that it tends to be easily oxidized by the air or metals, and in the case of using the oxidized color developing solution in order to form color images, increase in fog, changes in sensitivity and gradation occur and desired photographic properties cannot be obtained.
In particular, with the recent trend of shortening time for processing, the change in photographic properties tends to increase during continuous processing and a severe problem of color stain formation may occur in some cases. Particularly, such a problem is apt to occur when a desilvering step and a water washing step are shortened.
Various reasons for the change in photographic properties and the occurrence of color stain in continuous processing are considered likely. For example,
A: a color developing solution is degraded with the lapse of time, as a result, the photographic properties change and the oxidation product of a developing agent adheres to photographic light-sensitive materials, resulting in the formation of color stain; PA0 B: a color developing agent is carried over into a bleaching solution or a bleach-fixing solution and oxidized to form fog and stain, PA0 C: a substance dissolved out from photographic light-sensitive materials is accumulated in a color developing solution and adheres to the photographic light-sensitive materials to form color stain, PA0 D: due to insufficient washing out of dyes or sensitizing dyes incorporated in photographic light-sensitive materials the photographic light-sensitive materials are colored; or PA0 E: a bleach-fixing solution or a subsequent rinse solution is degraded with the lapse of time and color stain occurs. PA0 D-1: N,N-Diethyl-p-phenylenediamine PA0 D-2: 4-[N-Ethyl-N-(.beta.-hydroxyethyl)amino]aniline PA0 D-3: 2-Methyl-4-[N-ethyl-N-(.beta.-hydroxyethyl)amino]aniline PA0 D-4: 4-Amino-3-methyl-N-ethyl-N-[.beta.-(methanesulfonamido)ethyl]aniline PA0 Nitrilotriacetic acid PA0 Diethylenetriaminepentaacetic acid PA0 Ethylenediaminetetraacetic acid PA0 Triethylenetetraminehexaacetic acid PA0 N,N,N-Trimethylenephosphonic acid PA0 Ethylenediamine-N,N,N',N'-tetramethylenephosphonic PA0 1,3-Diamino-2-propanoltetraacetic acid PA0 Trans-cyclohexanediaminetetraacetic acid PA0 Nitrilotripropionic acid PA0 1,2-Diaminopropanetetraacetic acid PA0 Hydroxyethyliminodiacetic acid PA0 Glycol ether diamine tetraacetic acid PA0 Hydroxyethylenediaminetriacetic acid PA0 Ethylenediamine o-hydroxyphenylacetic acid PA0 2-Phosphonobutane-1,2,4-tricarboxylic acid PA0 1-Hydroxyethylidene 1,1-diphosphonic acid PA0 N,N'-Bis(2-hydroxybenzyl)ethylenediamine-N,N'-diacetic acid PA0 Ethylenediaminetetraacetic acid PA0 Diethylenetriaminepentaacetic acid PA0 1,3-Diaminopropanetetraacetic acid PA0 Propylenediaminetetraacetic acid PA0 Nitrilotriacetic acid PA0 Cyclohexanediaminetetraacetic acid PA0 Methyliminodiacetic acid PA0 Iminodiacetic acid PA0 Glycol ether diaminetetraacetic acid
Particularly, in order to solve problems A and B, it is an indispensable condition to improve the stability of a color developing solution. A sulfite ion has been well known as a preservative for the purpose of increasing stability of a color developing solution. It is also known that incorporation of various sulfites into a color developing solution is effective to prevention from color stain. On the other hand, such a sulfite ion has undesirable effects on photographic properties, in that it deteriorates color forming properties and dissolves silver halide.
In recent years, it has been strongly desired to accelerate processing, that is, to shorten the time necessary for processing. In color development processing, there is a strong need to shorten the time for the desilvering step which occupies nearly one half of the total processing time.
In general, ferricyanides, dichromates, ferric chloride, aminopolycarboxylic acid ferric complex salts, and persulfates are known as bleaching agents.
However, both ferricyanides and dichromates have the problem of environmental pollution with respect to cyanide compounds and hexa-valent chromium compounds. Thus, their use requires special treatment equipment. Ferric chloride also has various practical problems of the formation of iron hydroxide and the occurrence of stain during a water washing step provided thereafter. With respect to persulfates, there is a problem that their bleaching function is very weak and thus a substantially long bleaching time is required.
On the other hand, aminopolycarboxylic acid ferric complex salts (particularly, ethylenediaminetetraacetic acid ferric complex salt) are bleaching agents most widely employed at present, in view of reduced problems of environment pollution and no problem of storage. In order to render the desilvering step rapid, there have been known a bleach-fixing solution, which contains an aminopolycarboxylic acid ferric complex salt and a thiosulfate in a single solution, as described in German Patent No. 866,605. However, the bleaching power of the solution is very weak, since an aminopolycarboxylic acid ferric complex salt which is weak in oxidizing power (bleaching power) and a thiosulfate which has a reducing power coexist in a single solution. Therefore, it is very difficult for the bleach-fixing solution to sufficiently achieve desilvering of color photographic light-sensitive materials and consequently it can not be employed for practical use.
Therefore, for the purpose of increasing the bleaching power there has been proposed a method wherein various bleach accelerating agents are added to a bleaching bath, a bleach fixing bath or a prebath thereof. Examples of such bleach accelerating agents include ammonium bromide as described in JP-A-Nos. 51-87036 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), a water-soluble iodide salt as described in British Patent No. 926,569, and a halide salt as described in JP-B-Nos. 53-11854 (the term "JP-B" as used herein means an "examined Japanese patent publication").
However, it has been found that when these halide salts are added to a bleach-fixing solution, the desilvering property is not sufficiently improved and they are almost in effective to prevent color stain which may occur in the case of rapid processing or continuous processing of color photographic light-sensitive materials.
Further, when bleach-fixing processing is conducted using a bleach-fixing solution containing an aminopolycarboxylic acid metallic complex salt such as EDTA ferric complex salt, just after a step with a reducing agent is carried over to the bleach-fixing bath with the photographic material and the aminopolycarboxylic acid metallic complex salt is reduced with the reducing agent ptesent in the bleach-fixing solution. The resulting reduction product of aminopolycarboxylic acid metallic complex salt may reduce a colored dye formed, particularly a cyan dye, to form a leuco dye, and as a result, insufficient color restration occurs.